It is known that gradual release of fertilizer nutrients and biologically active agents such as pesticides into the soil is more advantageous for pest control, plant growth, and seed germination, as this avoids undesirable plant toxicity resulting from sudden increases in soil concentrations of applied substances.
Many controlled release methods for fertilizers and pesticides have previously been disclosed. For example, in U.S. Pat. No. 5,484,600, Sjogren discloses a method for making a composite particle capable of releasing insecticides at a slow or controlled rate. In U.S. Pat. No. 5,576,008, Yang et al. disclose a method for the microencapsulization of insecticides into a urea-formaldehyde resin. In U.S. Pat. No. 5,516,520, Yang et al. disclose a method of preparation and use of a pesticide encapsulated in a starch-borax-urea matrix for controlled release. In U.S. Pat. No. 5,565,407, Southard discloses improved bioactive agent release-extending compositions of native, undenatured starch and biodegradable synthetic polymers. In U.S. Pat. No. 5,652,196, Luthra et al. disclose products for the variable controlled release of water soluble plant nutrients consisting of a core of water soluble agent coated with an organic film-forming thermoplastic or thermosetting compound and a thermoplastic resin to control release. In U.S. Pat. No. 5,429,654, Swarup discloses a method of improved fertilizer release control comprising coating a fertilizer with a neutralized, sulfonated EPDM polymer having a measurable degree of crystallinity. In U.S. Pat. No. 5,750,130, Ferrell et al. disclose a method of applying a pesticide to inert organic or inorganic granular substrates using a carrier compound to improve adhesion of the pesticide to the substrate and to improve control over the release of the pesticide.
It is desirable to avoid the use of foreign materials or materials which are not otherwise useful for growing plants when developing methods for the more effective utilization of fertilizers and pesticides, as this allows for enhanced growth and protection of plants without the introduction of complex and expensive matrix components.
In U.S. Pat. Nos. 5,391,542 and 5,143,939, Browning discloses the use of surfactants such as the TERGITOL series of surfactants (TERGITOL is a registered trademark of Union Carbide Corporation, Danbury, Conn.) as a liquid soil additive to enhance the germination and subsequent growth of plants. Browning also describes the use of the liquid soil additive as a method of nematode, worm, mite, and fungus control. However, the surfactant is only effective for a limited period of time following application to the soil.
There exists a need in the art for an improved soil treatment which is efficacious over a longer period of time and avoids the use of extra foreign materials or matrix components. Such a treatment should ideally enhance plant germination and growth while allowing for the control of agricultural pests. The treatment should also control the release of the agricultural products so as to prevent concentration fluctuations that may be toxic to plants. In so doing, the number of required applications will be reduced due to a decrease in the amount of leaching.